Tanning compositions comprising aqueous solutions of unsaturated acid-unsaturated sulfated oil copolymers



United States Patent 3,408,319 TANNING COMPOSITIONS COMPRISING AQUE- OUSSOLUTIONS OF UNSATURATED ACID-UN- SATURATED SULFATED OIL COPOLYMERSWilliam J. Rau, Wyndmoor Valley, Pa., assignor to Rohn & Haas Company,Philadelphia, Pa., a corporation of Delaware No Drawing. Filed Dec. 8,1964, Ser. No. 416,874 17 Claims. (Cl. 260-43) ABSTRACT OF THEDISCLOSURE Tanning compositions are made by copolymerization of amixture of (A) methacrylic acid, acrylic acid or mixtures of such acidswith (B) a sulfated unsaturated oil. The unsaturated acid used ispreferably 75 to 100% methacrylic acid and 25 to 0% respectively ofacrylic acid, and generally the use of methacrylic acid exclusively ismost practical from the standpoint of cost and effectiveness. The amountof sulfonated oil is from to 25% by weight of the acid monomer.

The present invention is concerned with the tanning of leather.

It is already known that various skins or hides can be tanned by theapplication of polyacrylic acid, polymethacrylic acid or copolymers ofthese acids. These materials may be used as the sole tanning agents orthey may be used as pretanning or retanning agents preceding orfollowing respectively the application of other tanning agents such aschrome, zirconium, natural tannins, and synthetic tanning agents. Theuse of these agents has an important disadvantage, however, in that theyfrequently impart crackiness to the grain of the leather and this evenoccurs in some instances with heavily fat-liquored skins. Most synthetictanning agents do not cause cracking in this fashion even when appliedwithout fat-liquoring. Compositions made up with the tanning agent and afat-liquoring agent such as an oil, have the disadvantage that there isgross separation of the oil from the composition on storage after a fewdays.

It is an object of the present invention to provide a new compositionhaving advantageous tanning properties. It has been discovered that suchtanning compositions can be made by copolymerization of a mixture of (A)methacrylic acid, acrylic acid or mixtures of such acids with (B) asulfated unsaturated oil. The unsaturated acid used is preferably 75 to100% methacrylic acid and 25 to 0% respectively of acrylic acid, andgenerally the use of methacrylic acid exclusively is most practical fromthe standpoint of cost and etfectiveness. The amount of sulfated oil isfrom 10 to 25% by weight of the acid monomer. Preferably, the amount ofsuch oil is about to based on the weight of the monomer.

The sulfated oil with which the unsaturated acid is polymerized is onein which the extent of sulfation has not been so great as to completelyeliminate points of unsaturation in the product. Thus, the extent ofsulfation may be such as to remove all points except one of unsaturationin the oil. In those oils which also contain hydroxyl groups, thesulfation may be exerted exclusively On the hydroxyl groups leaving allof the points of unsaturation essentially untouched or the sulfation mayconvert both the hydroxyl groups and part of the unsaturated groups intosulfates. For example, in olive oil, which contains as a majorconstituent a glyceride of oleic acid, sulfation may introduce sulfategroups on one or two of the three points of unsaturation in theglyceride molecule leaving one or two of the unsaturated groupsessentially untouched or unmodified. While olive oil is mentioned theremay be used instead any of the other animal and vegeice table oilscontaining one or more glycerides of unsaturated acids having longchains such as from 12 to 20 carbon atoms. Examples of these oilsinclude:

Almond Peanut Beechnut Poppy seed Black mustard Porpoise (body oil)Candlenut Pumpkin seed Castor Rape seed Chaulmoogra Satfiower Cod liverSeal Corn (maize) Sesame Cotton seed Soja bean (soya, soy) Lard oilSperm Linseed Sunflower Menhaden Tung (China wood) Neats-foot WalnutPalm Whale The preparation of the still partially unsaturated sulfationproducts of these oils is well known and in fact, many are commerciallyavailable.

The copolymerization is effected in an aqueous medium in which thesulfated oil is dissolved, for example at a concentration of 5% to 15%by weight. To this solution there is added a water-solublepolymerization initiator and, optionally, a water-soluble chain-transferagent. An aqueous solution of a chain-transfer agent, if such an agentis used, may also be dissolved directly in the monomer and this solutionmay then be added to the sulfated oil/ catalyst solution in the flask.The sulfated oil/catalyst solution (which may also contain achain-transfer agent) may be held at room temperature or raised to ashigh as 97 C. or even higher (such as to reflux) and maintained at thedesired temperature while adding the acid monomer. The addition of theacid monomer results in copolymerization of such acid with theunsaturated sul-' fated oil yielding the product of the presentinvention which is highly effective as a tanning agent for leather andhas the advantage of effecting tannage without imparting crackiness tothe grain of the leather even without fat-liquoring the leather.

The relative proportions of the acid monomer and sulfated oil are and byweight of monomer to 20 to 10% by weight respectively of the oil. Inother words, the amount of monomer used is about 4 to 8 times the amountof sulfated oil. The proportion of initiator is from 0.5 to 6% by weightof the monomer. Examples of initiators include hydrogen peroxide,ammonium persulfate, sodium persulfate, and potassium persulfate.

The proportion of chain transfer agent depends on the particular agentand its effectiveness in controlling the molecular weight of thecopolymer. In general, the amount of chain transfer agent used iscorrelated with the amount of initiator so as to result in theproduction of a copolymer which in acid form at approximately 33%concentration in water and at 25 C. will have a viscosity in the rangeof about 15 to 300 poises. No chain-transfer agent is needed if theproportion of initiator used is high enough to produce a copolymer oflow molecular weight in the range specified. It is estimated that themost suitable molecular weight range of the product is from about 5,000to 50,000 number average. Examples of chain-transfer agents includehydroxylamine or salts thereof, such as hydroxylamine sulfate,mercaptoethanol, mercaptopropanol, thiodiglycol, thioglycollic acid,ascorbic and isoascorbic acid. The chain-transfer agent may be used inan amount of about 0.2 to 3.5% by weight based on the weight of themonomer.

The copolymers of the present invention are water-soluble and dilutable.They remain in solution indefinitely without signifiicaut separation ofoil content and are capable of tanning skins or hides without impartingcrackiness to the grain.

For the purpose of tanning hides or skins, the copolymer is dissolved inwater at a concentration of about 5 to 40% by weight. Of course, thecopolymer need not be isolated from the aqueous solution in which it isprepared. Such solutions need only be adjusted to the desiredconcentration for use in tanning. A salt, such as sodium chloride orsodium sulfate, is included in the tanning solution at a concentrationof 3 to 8% by weight. The tanning liquor is introduced into a suitablevessel such as the conventional tanning drum and then the skins areintroduced into the drum. The weight of skins relative to the weight ofliquor is generally determined to provide about 20 to 25% of activetanning agent based on the weight of wet pickled skin and about 5 to 15%of salt, when used, on the weight of skin. The tanning is effected bytumbling the skin within the drum or vessel at room temperature up tobut not above 35 C. Most commonly, the temperature may extend between 28and 32 C. The tumbling in the tanning liquor may be carried out for anumber of hours such as from 4 to 24 hours.

This tannage may be followed by a mineral tanning, vegetable extracttanning, or synthetic tanning agent.

In the retanning of skins which have previously been mineral-tanned,especially chrome-tanned, or zirconium tanned or tanned by other means,the concentration of the copolymer may be from /2 to 10% by weight inthe tanning liquor. Generally, there is no salt used in this tanningliquor and the amount of the tanning liquor relative to the partiallytanned leather treated therewith is such as to provide about 1% to 5% ofthe copolymer based on the weight of the wet chrome leather. This meansthat to provide 3% on the leather there would be used 200% based on theweight of leather of a liquor containing 1 /2% of the copolymer.

The tanning composition of the present invention may be employed for thetreatment of all types of skins and hides, such as horsehide, cowhide,kidskin, lambskin, goatskin, pigskin and so on. The tanned products areadapted for use in all types of leathers such as shoe, sole and upper,garment, case, upholstery and industrial leathers.

To assist those skilled in the art to practice the present invention,the following modes of operation are suggested by way of illustration,parts and percentages being by weight and the temperatures in C. unlessotherwise specifically noted.

(1) Three solutions are prepared as follows:

Solution A:

312 g. aqueous sulfated castor oil (234 g. actual oil) a Solution A isheated in a glass reaction vessel to 90 C. Solutions B and C are addedgradually simultaneously over a 50-minute period through suitabledevices, such as dropping funnels, to feed the reaction vessel, holdingthe temperature at 89 to 93 C. The mixture is heated 1 hours longer at90 C. (:1" C.). It is then cooled, while agitating, to 70-75 C. There isthen added 0.1% phenol (based on product) and stirring is continuedanother minutes at 7075 C. The 33 /a% solids copolymer solution weighs4268 g. and has a viscosity of 33 poises at C. (Brookfield LVFviscometer, No. 3 spindle at 12 r.p.m.)

(2) Tannage of pickled skin.-Thirty-eight grams of pickled calfskin isput into a bottle. To this is added a tanning solution comprised of:

4 27 grams of the 33Va% solids tanning material (obtained in 1 above)3.8 grams of NaCl 76 ml. of water This bottle is sealed and is agitatedin a shaking machine for 24 hours. Then 1.5 g. of sodium acetate isadded and the bottle is shaken 3 hours longer; then the liquor isdrained. The skin is washed thoroughly with water, fat liquored with amixture of 0.3 g. Texol N (a commercial sulfated meats-foot oil), 0.08g. meats-foot oil, and 57 ml. of water, shaken one hour, set out anddried; and finally sammied and staked.

An excellent piece of White leather is obtained which shows outstandinglightfastness and very good ageing characteristics.

(3) Two solutions are prepared:

Solution A:

105 ml. water 1.75 g. ammonium persulfate Solution B:

50 g. methacrylic acid (MAA) 13 g. aqueous sulfated sperm oil (10 g.actual oil) Solution A is heated to C. Solution B is added 10 Solution Aover a 40-minute period. The mixture is stirred 1 /2 hours at 90-95 C.There is then added 1.5 g. ammonium hydroxide (28% NH followed bystirring 15 minutes longer at 9095 C. The mass is agitated while coolingto approximately 70 C. The product is a 35% solids solution ofcopolymer. At 25 C. and 33% concentration, it has a viscosity of 70poises.

(4) Retannage of chrome leather. -Twentythree grams of chrome-tannedcalfskin is put into a bottle. To this there is added a tanning solutioncomprised of:

2.5 grams of the tanning agent 35% solution obtained in 3 above 46 ml.of water This is agitated in a shaking machine for 1 hours. Then theliquor is drained, and the resulting leather is washed thoroughly.Finally it is set out, dried, sammied, and staked. The leather obtainedshows excellent fullness and is well bleached, being much superior tochrome leather which had not been retanned. The leather also showsexcellent lightfastness and ageing properties.

(5) Three solutions are prepared:

Solution A:

160 ml. water 2.0 g. hydroxylamine sulfate 26 g. aqueous sulfatedneats-foot oil (20 g. actual oil) Solution B:

g. methacrylic acid (MAA) Solution C:

3.3 g. hydrogen peroxide (30%) 50 ml. water Solution A is heated to 90C. Solutions B and C are then added gradually and simultaneously over a40-minute period while stirring. Then 0.7 g. H 0 is added quickly. Themixture is stirred 1 /2 hours longer at 90-95 C. Then there is added anammonium hydroxide solution (2 g. of 28% NH +4 ml. H O) over a 1-minuteperiod. The mixture is stirred 20 minutes longer at 90-95 C. and thenwhile continuing the agitation, it is cooled to approximately 70 C. Theproduct is a 35% solids solution of the copolymer. At 25 C. and 33%concentration, it has a viscosity of 40 poises.

(6) Retannage of zirconium-tanned leather.Fortyone grams of zirconiumtanned calfskin is put into a bottle. To this there is added a tanningsolution comprised of:

6.8 g. of the 35 solution of tanning agent of 5 above 82 ml. of water. i

This is shaken for 3 hours. The liquor is drained and the leather iswashed thoroughly. It is then fat-liquored with 1.64 g. of Albinoil 300W (a commercial sulfated heats-foot oil) and 0.41 g, oil in 63 ml. ofwater; finally set out, crusted, sammied and staked. The white leatherobtained shows excellent fullness and color.

(7) Three solutions are prepared:

Solution A:

190 ml. water 30 ml. hydroxylamine solution-1.02 actual HA. 26 g.aqueous sulfated codfish oil (20 g. actual oil) Solution B:

90 g. methacrylic acid (MAA) g. acrylic acid (AA) Solution C:

2.9 g. hydrogen peroxide (35%) 50 ml. water Heat Solution A to 90 C. AddSolutions B and C simultaneously over a period of 40 minutes. Add 0.5 g.H 0 (35%) quickly. Stir 1 hours longer at 8992 C. Let agitate whilecooling to approximately 70 C. The product is a 30.5% solution of acidcopolymer. At 25 C. and 33% concentration, it has a viscosity of 35poises.

(8) Pretannage of mineral tanned leather.-Forty-one grams of pickledcalfskin is put into a bottle. To this there is added a tanning solutioncomprising:

6.9 g. of the 30.5% solution of tanning agent obtained 4.1 g. of NaCl 82ml. of water This is shaken for 18-20 hours. The pretanned leather isthen tanned in the normal way with 9.9 g. of basic zirconium sulfate.After tannage, the skin is washed thoroughly and fat-liquored with 1.64g. Albinoil 300 W and 0.41 g. meats-foot oil in 63 ml. water. Finallythe piece is set out, crusted, sammied, and staked. The leather obtainedshows excellent fullness and color.

(9) Two solution are prepared:

Solution A:

200 ml. water 13 g. aqueous sulfated soybean oil (10 g. actual oil) 0.25g. lauroyl peroxide Solution B:

50 g. methacrylic acid (MAA) 50 ml. water 1.5 g. mercaptoethanol HeatSolution A to 90 C. Add Solution B over a period of 45 minutes. One hourlater, add a solution of 0.8 g. ammonium persultate in 7 ml. water. Stir1 hour at 90 C. (:1 C.). Let agitate While cooling to 34-40 C. Vacuumstrip-weight of distillate =107 g.; final copolymer solution weight is212 g. (approximately 28% solids). At 25 C. and 33% concentration, ithas a viscosity of 34 poises.

(10) Retannage of chrome-tanned calfskin with polymeric tanning agentand vegetable tanning agent.A thirty-gram piece of chrome-tannedcalfksin is put into a bottle. To this there is added a tanning solutioncomprising:

1.8 g. of the 28% solution of tanning agent 9 above 60 ml. of water Thisis shaken for 2 hours; then the liquor is drained and the tanned pieceis rinsed. Then the following solution is added:

1.2 g. of quebracho powder 60 ml. of water This is shaken for 2% hoursand the liquor is drained; then the piece is washed thoroughly andfat-liquored with 0.60 g, of sulfated heats-foot oil in 45 ml. of water,and finally set out, dried, sammied, and staked. An excellent piece ofleather is obtained showing a very light color, superior light fastness,and good fullness and roundness.

6'. (ll) Acid/sulfated oil copolymer solutions of'approxi mately 30%concentration are obtained by repeating procedure 7 except that thesulfated. codfish oil is replaced by (a) sulfated castor oil (b)sulfated meats-foot oil (0) sulfated sperm oil (d) sulfated soybean oilEach of the resulting copolymer solutions may be used for tanning,retanning or pretanning as in any of procedures 2, 4, 6, 8 and 10.

(12)(a) Acid/sulfated oil copolymer solutions of approximately 30%concentration are obtained by repeating procedure 7 except that SolutionB is replaced by a mixture of g. of methacrylic acid and 25 grams ofacrylic acid.

(b) Part (a) is repeated except that the sulfated codfish oil isreplaced by (a) sulfated castor oil (b) sulfated neats-foot oil (c)sulfated sperm oil (d) sulfated soybean oil Each of the resultingcopolymer solutions may be used for tanning, retanning or pretanning asin any of procedures 2, 4, 6, 8, and 10.

I claim:

1. As a composition of matter, a copolymer of a mix ture of (A) to byweight of an acid selected from the group consisting of acrylic acid,methacrylic acid, and mixtures thereof and (B) 20 to 10% by weight of anunsaturated sulfation product of an oil selected from the groupconsisting of animal and vegetable oils.

2. As a composition of matter, a copolymer of a mixture of (A) 80 to 90%by weight of an acid selected from the group consisting of acrylic acid,methacrylic acid, and mixtures thereof and (B) 20 to 10% by weight of anunsaturated sulfation product of an oil selected from the groupconsisting of animal and vegetable oils, a 33% solution in water of saidcopolymer in acid form at 25 0., having a viscosity of about 15 to 300poises.

3. As a composition of matter, a copolymer of a mixture of (A) 80 to 90%by weight of methacrylic acid and (B) 20 to 10% by weight of anunsaturated sulfation product of a vegetable oil.

4. As a composition of matter, a copolymer of a mixture of (A) 80 to 90%by weight of methacrylic acid and (B) 20 to 10% by weight of anunsaturated sulfation product of an animal oil.

5. As a composition of matter, a copolymer of a mixture of (A) 80 to 90%by weight of methacrylic acid and (B) 20 to 10% by weight of anunsaturated sulfation product of castor oil.

6. As a composition of matter, a copolymer of a mixture of (A) 80 to 90%by weight of methacrylic acid and (B) 20 to 10% by weight of anunsaturated sulfation product of neats foot oil.

7. As a composition of matter, a copolymer of a mixture of (A) '80 to90% by weight of methacrylic acid and (B) 20 to 10% by weight of anunsaturated sulfation product of sperm oil.

8. As a composition of matter, a copolymer of a mixture of (A) 80 to 90%by weight of methacrylic acid and (B) 20 to 10% by weight of anunsaturated sulfation product of codfish oil.

9. As a composition of matter, a copolymer of a mixture of (A) 80 to 90%by weight of methacrylic acid and (B) 20 to 10% by weight of anunsaturated sulfation product of soybean oil.

10. As a composition of matter, a copolymer of a mixture of (A) 80 to90% by weight of a mixture of at least 75% by weight of methacrylic acidand up to 25% by Weight of acrylic acid and (B) 20 to 10% by weight ofan unsaturated sulfation product of castor oil.

11. As a composition of matter, a copolymer of a mixture of (A) 80 to90% by weight of a mixture of at least 7 75% by weight of methacrylicacid and up to 25% by weight of acrylic acid and (B) 20 to 10% by weightof an unsaturated sulfation product of meats-foot oil.

12. As a composition of matter, a copolymer of a mixture of (A) 80 to90% by weight of a mixture of at least 75 by weight of methacrylic acidand up to 25% by Weight of acrylic acid and (B) 20 to 10% by Weight ofan unsaturated sulfation product of sperm oil.

13. As a composition of matter, a copolymer of a mixture of (A) 80 to90% by weight of a mixture of at least 75 by weight of methacrylic acidand up to 25% by weight of acrylic acid and (B) 20 to 10% by weight ofan unsaturated sulfation product of codfish oil.

14. As a composition of matter, a copolymer of a mixture of (A) 80 to90% by Weight of a mixture of at least 75 by weight of methacrylic acidand up to 25 by weight of acrylic acid and (B) 20 to 10% by weight of anunsaturated sulfation product of soybean oil.

15. In an aqueous composition for tanning leather, the improvementwherein a copolymer of a mixture of (A) 80 to 90% by weight of an acidselected from the group consisting of acrylic acid, methacrylic acid,and mixtures thereof and (B) 20 to 10% by weight of an unsaturatedsulfation product of an oil selected from the group consisting of animaland vegetable oils serves as a tanning agent therein.

16. As a tanning composition, an aqueous solution containing to 40% byWeight, based on the total solution weight, of a copolymer of a mixtureof (A) 80 to 90% by weight of an acid selected from the group consistingof acrylic acid, methacrylic acid, and mixtures thereof and (B) to 10%by weight of an unsaturated sulfation product of an oil selected fromthe group consisting of animal and vegetable oils, a 33% solution inwater of said copolymer in acid form at C., having a viscosity of about15 to 300 poises.

17. As a tanning composition, an aqueous solution containing 3 to 8% byweight, based on the total solution weight of a salt selected from thegroup consisting of sodium chloride and sodium sulfate, and 5 to 40% byweight, based on the total solution weight, of a copolymer of a mixtureof (A) to by weight of an acid selected from the group consisting ofacrylic acid, methacrylic acid, and mixtures thereof and (B) 20 to 10%by weight of an unsaturated sulfation product of an oil selected fromthe group consisting of animal and vegetable oils, a 33% solution inwater of said copolymer in acid form at 25 C., having a viscosity ofabout 15 to 300 poises.

References Cited UNITED STATES PATENTS 2,205,883 6/1940 Graves 8-94.332,280,310 4/ 1942 Koppenhoefer et a1. 8-94.22 2,452,536 11/1948 Kirk8-94.21 3,231,420 1/1966 Lowell et al 117-142 3,245,832 4/ 1966 Doggettet a1 8-94.23 3,291,558 12/1966 Bader et a1. 117-142 DONALD E. CZAJA,Primary Exdminer.

R. W. WHITE, Assistant Examiner.

